Pump for liquids which emit corrosive fumes

ABSTRACT

A pump including body having an inlet and an outlet. Upper and lower impellers rotate within the body, the lower impeller moving a liquid, which emits corrosive fumes, from the inlet to the outlet, and the upper impeller tending to move liquid downwardly toward the lower impeller. A liquid, e.g., water, having no corrosive fumes is sprayed into the pump body above the upper impeller to block the corrosive fumes which rise from the liquid being pumped by the lower impeller. The spray may be in the form of a mist or it may be a continuous liquid flow.

United States Patent 1 91 Otto [ 1 PUMP FOR LIQUIDS WHICH EMIT CORROSIVE FUMES [75] Inventor: Walter J. Otto, Wantagh, N.Y.

[73] Assignee: Julius L. Englesberg, Freeport, N.Y.

[22] Filed: June 24, 1971 [21] Appl. No.: 156,212

[52 us. Cl ..415/109, 415/116 51] int. Cl. ..F0ld 11/00, F04d 31/00 [58] Field at Search ..415/109,111,112, 116; 416/223 [561 References Cited UNI ED STATES PATENTS 3,610,416 10/1971 0110 ..415/100 FOREIGN PATENTS OR APPLICATIONS 369,966 3/1922 GreatBritain ..415/109 1451 Jan. 23, 1973 928,588 6/1947 France .A15/109 404,134 1/1934 Great Britain... ..415/116 1,034,032 7/1958 Germany ..415/109 304,489 3/1925 Switzerland ..416/223' Primary Examiner-Henry F. Raduazo Attorney-Alan H. Levine [5 7] ABSTRACT A pump including body having an inlet and an outlet. Upper and lower impellers rotate within the body, the lower impeller moving a liquid, which emits corrosive fumes, from the inlet to the outlet, and the upper impeller tending to move liquid downwardly toward the lower impeller. A liquid, e.g., water, having no corrosive fumes is sprayed into the pump body above the upper impeller to block the corrosive fumes which rise from the liquid being pumped by the lower impeller. The spray may be in the form of a mist or it may be a continuous liquid flow.

8 Claims, 2 Drawing Figures PATENTEDJM 23 1915 INVENTOR W141 727? (Z 0770 BY E g Q I 2 fTTORNEYS 1. PUMP FOR LIQUIDS WHICH EMIT CORROSIVE FUMES This invention relates to centrifugal pumps, and more particularlyto such a pump including upper and lower impellers on a single shaft, the lower impeller serving to pump liquid from the pump inlet to the pump outlet and the upper impeller serving as a dynamic seal.

In such a pump, some of the liquid being pumped by the lower impeller flows around its peripheral edge and travels up the rotating shaft. The upper impeller is arranged to pump liquid downwardly toward the lower impeller and hence serves as a barrier to liquid traveling up the shaft. As a result, no'stationary seals around the shaft are needed. This is particularly advantageous when a liquid, such a nitric acid, which emits corrosive fumes is being pumped, since such fumes corrode seals and require that they be replaced often.

However, since stationary seals serve as a barrier to fumes but a dynamic seal impeller does not, eliminating stationary seals allows corrosive fumes to rise out of the impeller cavity. Suchfumes may damage the motor which drives the impeller shaft, and may get into the atmosphere where they are potentially harmful to personnel and other equipment.

It is an object of the present invention to provide such a pump employing no stationary seals around the impeller shaft, but which nevertheless furnishes a reliable barrier to corrosive fumes emitted by the liquid being pumped.

lt is a more specific object of the invention to provide means for spraying a liquid which emits no corrosive fumes into thepump body above the upper impeller. The liquid spray forms a barrier to fumes rising from the liquid being pumped. Furthermore, the sprayed liquid is moved by the upper impeller downwardly toward the lower impeller, where it mixes with the liquid being pumped and is discharged through the pump outlet.

The present invention may be used in any situation in which addition of the sprayed liquid to the liquid being pumped is acceptable. For example, a pump according to this invention may be used to recirculate the water used in a fume scrubber, this water becoming more and more acidic each time it is passed through the deleterious vapors being scrubbed.

Additional objects and features of the invention will be apparent from the following description in which reference is made to the accompanying drawing.

FIG. I is a vertical cross-sectional view through a pump according to the present invention; and

FIG. 2 is a horizontal cross-sectional view taken on line 2--2 of FIG. 1.

The pump chosen to illustrate the present invention includes a pump body formed at its upper end with a flange 12 upon which is seated a bracket 14 supporting an electric motor 13 for driving the pump. Motor 13 is fixed to bracket 14 by screws 15, and bracket 14 is fixed to flange 12 by screws 16. Pump body 10 is formed at its lower end with a flange 17 to which a bottom wall 21 is fastened by screws 19. A seal 18 is provided between flange l7 and bottom wall 21.

Within pump body 10 is an impeller cavity 20 defined at its lower end by the bottom wall 21, and at its upper end by a top wall 22 projecting inwardly from the wall of the pump body. The impeller'cavity is furnished with an inlet 23 in the center of wall 21, the inlet being threaded to receive a conduit connection. Adjacent to bottom wall 21, the side wall of body 10 is formed with an outlet 26 carrying suitable connection means 27.

Fixed to the motor shaft 29 is the upper end of an impeller shaft 30, the lower end of which passes through an opening 31 in the wall 22 and into the impeller cavity 20. Within the cavity 20 are two impellers 32 and 33, which may be identical, both fixed to the impeller shaft 30. Impeller 32, at the lower end of shaft 30, is arranged when rotated to draw liquid in through inlet 23 and deliver it to outlet 26. Impeller 33, spaced above impeller 32, has a reverse orientation with respect to the latter impeller, and hence tends to draw liquid in through opening 31. Upper impeller 33 is spaced closer to top wall 22 of the impeller cavity 20 than the spacing between lower impeller 32 and the bottom wall 21. Consequently, impeller 33 develops a higher pressure than impeller 32, and the liquid drawn through opening 31 by impeller 33 is forced through outlet 26 together with the flow from inlet 23. Shaft 30 is preferably provided with a coating 34 of a tough material, such as a suitable plastic, resistant to corrosive fumes.

As the shaft 30 and impellers 32 and 33 rotate, liquid flows around the peripheral edge of impeller 32 and into the space between the impellers. Ordinarily this liquid would tend to travel up rotating shaft 30 and hence a seal would be provided around the shaft, perhaps between the shaft and the side wall of opening 31. However, due to the presence of impeller 33, which as mentioned above develops a higher pressure than impeller 32, no such seal is needed, since impeller 33 constantly urges the liquid which fills the cavity 20 downwardly, so that no liquid ever reaches the opening 31.

The spacing between impellers 32 and 33 is also important, since it allows a column of liquid to exist between the impellers. impeller 33, during its rotation, tends to suck air into the pump body, and if the blades of impeller 33 were simply mounted on the upper face of impeller 32, or if impellers 32 and 33 were arranged back-to-back, this air might be forced past the edge of impeller 32 and into outlet 26, especially since impeller 33 develops a higher pressure than impeller 32. However, the column of liquid between the impellers, within cavity 20, serves as a trap to prevent air from reaching impeller 32.

It will be appreciated that if the liquid being pumped emits corrosive fumes, these fumes are free to rise through the spaces between the peripheries of impellers 32 and 33, and through opening 31. These fumes can eventually reach motor 13 and damage it. The fumes may also escape into the atmosphere where they are potentially dangerous.

To prevent such escape of the corrosive fumes, the invention provides means for spraying a liquid into pump body 10 above the upper impeller 33. In the present example, this means is a nozzle 37 threaded into a bore in the wall of body 10, in a gas-tight manner. The exterior end of nozzle 37 is connected to a tube 38 for bringing a liquid which emits no corrosive fumes, such as water, to the nozzle. The liquid is under sufficient pressure so that a liquid spray 39 is emitted by nozzle 37 which completely fills the cross-sectional area of pump body in the vicinity of nozzle 37. This spray may be a mist, i.e., a liquid-air mixture, or it may be a continuous liquid flow. In either case, it forms a barrier to fumes rising from impeller cavity 20. Furthermore, as the liquid of spray 39 falls, it carries the fumes downwardly with it.

The liquid of spray 39 flows downwardly through opening 31, and from this point impeller 33 drives it downwardly past impeller 32 so that the latter discharges it through outlet 26 together with the liquid drawn in through inlet 23.

The invention has been shown and described in preferred form only, and by way of example, and many variations may be made in the invention which will still be comprised within its spirit. lt is understood, therefore, that the invention is not limited to any specific form or embodiment except insofar as such limitations are included in the appended claims.

What is claimed is:

l. A pump for liquids which emit corrosive fumes, comprising:

a. a pump body having an inlet and an outlet, said pump body including an impeller chamber defined by top and bottom walls, said top wall having an opening,

b. an impeller shaft extending vertically through said opening into said impeller chamber, said shaft being devoid of seals where it passes through said opening,

c. means for rotating said shaft,

d. upper and lower impellers, within said impeller chamber, fixed to and rotatable with said shaft, said lower impeller drawing corrosive-fumeemitting liquid in through said inlet and discharging it through said outlet, and said upper impeller tending to move liquid downwardly toward said lower impeller thereby eliminating the need for a seal around said shaft, and

e. means operable independently of the operation of said impellers for spraying a liquid having no corrosive fumes into said pump body above said upper impeller to block corrosive fumes which rise from the liquid being pumped by said lower impeller, said upper impeller moving said non-corrosive liquid downwardly toward said lower impeller.

2. A pump as defined in claim I wherein said upper impeller is arranged closer to said top wall then the spacing between said lower impeller and said bottom wall, so that said upper impeller develops a higher pressure than said lower impeller.

3. A pump as defined in claim 1 wherein said spray means includes a nozzle within said pump body and spaced above said top wall.

4. A pump as defined in claim 1 wherein said spray means includes a nozzle carried by said pump body, and means for transmitting liquid to said nozzle.

5. A pump as defined in claim 1 wherein said liquid spray means is constituted to provide a mist in said pump body above said upper impeller.

6. A pump as defined in claim 1 wherein said liquid spray means provides a continuous liquid flow.

7. A pump as defined in claim 1 wherein the liquid provided by said liquid spray means is water.

8. A pump as defined in claim 1 wherein said spray completely fills a cross-sectional area of said pump body. 

1. A pump for liquids which emit corrosive fumes, comprising: a. a pump body having an inlet and an outlet, said pump body including an impeller chamber defined by top and bottom walls, said top wall having an opening, b. an impeller shaft extending vertically through said opening into said impeller chamber, said shaft being devoid of seals where it passes through said opening, c. means for rotating said shaft, d. upper and lower impellers, within said impeller chamber, fixed to and rotatable with said shaft, said lower impeller drawing corrosive-fume-emitting liquid in through said inlet and discharging it through said outlet, and said upper impeller tending to move liquid downwardly toward said lower impeller thereby eliminating the need for a seal around said shaft, and e. means operable independently of the operation of said impellers for spraying a liquid having no corrosive fumes into said pump body above said upper impeller to block corrosive fumes which rise from the liquid being pumped by said lower impeller, said upper impeller moving said non-corrosive liquid downwardly toward said lower impeller.
 2. A pump as defined in claim 1 wherein said upper impeller is arranged closer to said top wall then the spacing between said lower impeller and said bottom wall, so that said upper impeller develops a higher pressure than said lower impeller.
 3. A pump as defined in claim 1 wherein said spray means includes a nozzle within said pump body and spaced above said top wall.
 4. A pump as defined in claim 1 wherein said spray means includes a nozzle carried by said pump body, and means for transmitting liquid to said nozzle.
 5. A pump as defined in claim 1 wherein said liquid spray means is constituted to provide a mist in said pump body above said upper impeller.
 6. A pump as defined in claim 1 wherein said liquid spray means provides a continuous liquid flow.
 7. A pump as defined in claim 1 wherein the liquid provided by said liquid spray means is water.
 8. A pump as defined in claim 1 wherein said spray completely fills a cross-sectional area of said pump body. 